The Microsoft 365 admin center has the option:
Let group owners add people outside of your organization to Microsoft 365 Groups as guests.
Tip: From the left menu in your admin center, click Show all > Settings > Org settings > Microsoft 365 Groups to display the option. For more information, see the Microsoft article Manage guest access in Microsoft 365 groups.
This option can be unchecked to prevent owners from adding guests to their teams and groups. The behavior of ShareGate Apricot depends on whether this setting is checked or unchecked.
- If the option is unchecked - The app cannot allow guest access to any team or group. You will not be able to update guest access from the team and group details. Certain sensitivity tag options may not be available.
- If the option is checked - You can edit membership and use the app's security features, such as the External sharing review policy and sensitivity tags to manage guest access.
For more troubleshooting information, see Why is a specific sensitivity tag or security setting invalid? or Why can't I add or remove members from a team or group?